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Join Date: Oct 2017
Posts: 80
1974 speedo failure

The Speedo in my '74 Carrera has suddenly given up the ghost...seems to be OK at very low speeds, but when i accelerate, there's a continuous loud, moderate-high pitched shriek and the needle goes absolutely spastic. Is this most likely to be in the gauge or the cable? Once dc'd, can you observe the cable's inner square cut cable for answer? thanx. steve
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Steve Meltzer
'74 Carrera New to me!
Old 01-03-2018, 06:24 AM
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Join Date: Oct 2005
Location: Capistrano Beach, Ca.
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It's possible to pull the speedo, disconnect the cable, and spin the speedo drive using a power drill with a square bit from a drive set. That should tell you whether or not the sound is coming from the speedo or the cable.
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L.J.
Recovering Porsche-holic
Gave up trying to stay clean
Stabilized on a Pelican I.V. drip
Old 01-03-2018, 07:08 AM
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Location: Atlanta, GA
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Could be either one, or both. Remove the speedo and monitor the cable as you accelerate.

Lubricate the cable and see if that helps. Graphite lube works pretty good for this.
Old 01-03-2018, 07:08 AM
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Thanx again, guys. Now, after serious prompting, I remember hearing about the power drill bit (pun intended). ?? this weekend. thanx s
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Steve Meltzer
'74 Carrera New to me!
Old 01-03-2018, 07:34 AM
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OK, i spoke with Kevin at Nichol's Speedometer in Greensboro, NC....recommended on another Pelican thread some time ago. He said the noise was almost certainly due to a bad speedo head. I know that doesn't rule out the cable, too, but on that mechanical speedo with a 915/tranny, can I just put in a new cable, or do I have to replace the entire unit, sheath and all? Also, if i just pull out the cable itself, can I replace it with a new cable (ie: will the new cable "find its way home" in the transmission), or is it more complex than that, making replacing the whole thing easier? I think the part number for that cable is 91164151000. thanx steve
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Steve Meltzer
'74 Carrera New to me!
Old 01-04-2018, 06:36 AM
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